Minimally invasive interspinous process spacer implants and methods

ABSTRACT

An interspinous process spacer for implantation in an interspinous space between a superior spinous process and an inferior spinous process includes a balloon-like body, a first deployable protrusion and a second deployable protrusion. The body has a distal end, a proximal end and a longitudinal axis extending between the proximal and distal ends. The spacer is arrangeable in an unexpanded configuration and an expanded configuration. The first deployable protrusion is mounted proximate the proximal end and the second deployable protrusion is mounted proximate the distal end. The first and second deployable protrusions are oriented generally parallel to the longitudinal axis in the unexpanded configuration and generally perpendicular to the longitudinal axis in the expanded configuration.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. patent application No.61/258,632, filed Nov. 6, 2009, and entitled “Minimally InvasiveInterspinous Process Spacer Implants and Methods,” which is incorporatedherein by reference in its entirety.

BACKGROUND

A human vertebrae has a rearwardly projecting portion known as a spinousprocess. Bending of the spine, particularly extension of the spine, cancause the spinous processes of adjacent vertebrae to move toward eachother. This constricts the space in the spinal canal and foramina andmay cause pain. Such pain may be exacerbated when the spinal canal ornerve roots exiting the canal are constricted by natural degeneration ofthe spine, such as by spinal stenosis or degenerative disc disease. Suchpain may be treated by positioning an implant in a space betweenadjacent spinous processes to maintain a predetermined distance betweenthe adjacent spinous processes, thereby providing a minimum amount ofspace between the spinous processes.

Generally there are two types of spinal stenosis: (1) hard or rigidspinal stenosis or (2) soft or dynamic spinal stenosis. In both cases,spinal stenosis may be caused by excessive growth of tissue due todegeneration, loss of disc height, excessive load in a particular areaof the spine as well disorders such as spondilolisthesis where thenormal relative position and/or orientation of the adjacent vertebraehave been modified.

A difference between the two types of spinal stenosis is that,generally, dynamic spinal stenosis may be treated with distraction ofthe vertebra at the affected level while hard stenosis generallyrequires removal of the tissue that obstructs the spinal canal orforamina at the affected level. In the case of tissue removal, thesurgical treatment typically results in some loss of stability to thespine. Therefore, it is preferable to increase the stability of thespinal segment by inserting an interspinous process spacer (“ISS”)between the spinous processes of the adjacent vertebrae to increase thestiffness of the segment and/or to restrict motion of that segment.

Some current implants are made of separate pieces that require insertionfrom both sides of the spinous processes using a posterior approach thatnecessitates rather wide openings into a patient, cutting both left andright thoracolumbar fascia, as well as stripping the multifidus musclesfrom their attachments. It is desirable to provide an implant forinsertion between the spinous processes of adjacent vertebrae that areinserted through a single opening in a minimal invasive approach and maybe held firmly in position between the vertebrae. It is desirable forthe surgical incision and surgical pathway to extend laterally into thespace between the adjacent spinous processes, thereby preserving majorligaments and musculature of the spine at the impacted level.

SUMMARY

The present disclosure relates generally to orthopedics. Morespecifically, the present disclosure relates to implants and methods forinterspinous process spacing using a minimally invasive surgicaltechnique, preferably using a preferred Interspinous Process Spacer(“ISS”).

In accordance with some implementations, there is provided aninterspinous process spacer for implantation in an interspinous spacebetween a superior spinous process and an inferior spinous process. Theinterspinous process spacer may include a central generally rigid rodmember having a distal end, a proximal end, and a longitudinal axisextending between the proximal and distal ends. The generally rigid rodmember may be arranged in an unexpanded configuration and an expandedconfiguration. A spacer portion may be disposed about the centralgenerally rigid rod member. The spacer portion may include one of arigid, elastomeric, or dampening material. A first plurality of wiresmay be disposed axially about the proximal end, and a second pluralityof wires disposed axially about the distal end. The first and secondplurality of wires may be oriented generally parallel to thelongitudinal axis in the unexpanded configuration and generallyperpendicular to the longitudinal axis in the expanded configuration.

In accordance with some implementations, there is provided aninterspinous process spacer for implantation in an interspinous spacebetween a superior spinous process and an inferior spinous process. Theinterspinous process spacer may include a central piston membercomprising a protruding distal stop surface, a generally rigid tubularmember comprising a proximal stop surface disposed about the centralpiston member and slidably translatable over the central piston memberand a flexible spacer portion disposed about the central piston memberand adjacent between the distal stop surface and the proximal stopsurface. In an unexpanded configuration, the distal stop surface and theproximal stop surface may be spaced at least as long as the length ofthe flexible spacer portion. In an expanded configuration, the distalstop surface and the proximal stop surface may be spaced at less thanthe length of the flexible spacer portion.

In accordance with yet other implementations, an interspinous processspacer for implantation in an interspinous space between a superiorspinous process and an inferior spinous process is provided. Theinterspinous process spacer may include a spacer body having a distalexpandable member, a central expandable member adjacent to and incommunication with the distal expandable member, and a proximalexpandable member adjacent to and in communication with the centralexpandable member. The spacer body may be arranged in an expandedconfiguration and compressible in an unexpanded configuration.

In accordance with further implementations, there is provided aninterspinous process spacer for implantation in an interspinous spacebetween a superior spinous process and an inferior spinous process. Theinterspinous process spacer may include a spacer body having a distalend, a proximal end, and a longitudinal axis extending between theproximal end and the distal end. A first proximal wing may beoperatively coupled to the proximal end wherein the first proximal wingis extendable perpendicular to the longitudinal axis. A first distalwing may be coupled to the distal end wherein the first distal wing isextendable perpendicular to the longitudinal axis. The first distal wingand the first proximal wing may extend beyond the bounds of the spacerbody in the expanded configuration, and the first distal wing and thefirst proximal wing may withdraw within the bounds of the spacer body inthe unexpanded configuration.

In accordance with other implementations, there is an interspinousprocess spacer for implantation in an interspinous space between asuperior spinous process and an inferior spinous process. Theinterspinous process spacer may include an implant body and a centralshaft that may extend through the implant body. The central shaft mayhave a distal end, a proximal end, and a longitudinal axis extendingbetween the proximal end and the distal end, where the central shaft isrotatable. The central shaft may further include a proximal worm geardisposed near the proximal end and a distal worm gear disposed near thedistal end. The interspinous process spacer may also include a firstproximal gear set, a first distal gear set, a first proximal wing and afirst distal wing. The first distal wing and the first proximal wing maywithdraw within the bounds of the implant body in the unexpandedconfiguration, and the first distal wing and the first proximal wing mayextend beyond the bounds of the implant body in the expandedconfiguration.

In accordance with yet other implementations, an interspinous processspacer for implantation in an interspinous space between a superiorspinous process and an inferior spinous process is provided thatincludes an implant body and an implant body exterior coating forcontact with at least one from among the superior spinous process andthe inferior spinous process. The coating may be compressible to providean anatomical fit.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofpreferred embodiments of the instrument, implant and method of thepresent application, will be better understood when read in conjunctionwith the appended drawings. For the purposes of illustrating theinterspinous process spacer (“ISS”) implants, instruments and methods ofthe present application, there are shown in the drawings preferredembodiments. It should be understood, however, that the application isnot limited to the precise arrangements and instrumentalities shown. Inthe drawings:

FIG. 1 illustrates a rear elevational view of an ISS implant inaccordance with a first preferred embodiment of the present disclosure;

FIGS. 2A-2C illustrate top perspective views of an ISS implant inaccordance with a second preferred embodiment of the present disclosurein an unexpanded, partially expanded, and fully expanded configuration,respectively;

FIGS. 3A-3C illustrate a cross-sectional and rear perspective views ofan ISS implant in accordance with a third preferred embodiment of thepresent disclosure in an unexpanded (FIG. 3A), partially expanded (FIG.3B), and fully expanded (FIG. 3C) configurations, respectively;

FIGS. 4A-4D illustrate rear elevational views of a variety of ISSimplants in accordance with a fourth preferred embodiment of the presentdisclosure;

FIGS. 5A-5D illustrate rear elevational views of an ISS implant inaccordance with a fifth preferred embodiment of the present disclosurein unexpanded, first partially expanded, second partially expanded, andfully expanded configurations, respectively;

FIGS. 6A and 6B illustrate rear elevational views of an ISS implant inaccordance with a sixth preferred embodiment of the present disclosurein unexpanded and expanded configurations, respectively;

FIGS. 7A and 7B illustrate rear elevational views of an ISS implant inaccordance with a seventh preferred embodiment of the present disclosurein unexpanded and expanded configurations, respectively;

FIGS. 8A and 8B illustrate rear elevational views of an ISS implant inaccordance with an eighth preferred embodiment of the present disclosurein unexpanded and expanded configurations, respectively;

FIGS. 9A-9C illustrate a side elevational view of an un-inflated ISSimplant in accordance with a ninth preferred embodiment of the presentdisclosure and a guide wire during its implantation, a rear elevationalview of the positioning of the guidewire prior to the insertion of theISS implant of FIG. 9A, and a rear elevational view of an inflated ISSimplant of FIG. 9A subsequent to its implantation, respectively.

FIG. 10 illustrates a rear elevational view of an ISS implant inaccordance with a tenth preferred embodiment of the present disclosure;

FIG. 11 illustrates a rear elevational view of an ISS implant inaccordance with an eleventh preferred embodiment of the presentdisclosure;

FIGS. 12A and 12B illustrate side elevational views of an ISS implant inaccordance with an twelfth preferred embodiment of the presentdisclosure in unexpanded and expanded configurations, respectively;

FIGS. 13A-13C illustrate a rear perspective view of an ISS implant inaccordance with a thirteenth preferred embodiment of the presentdisclosure in an unexpanded configuration, a rear perspective view ofthe ISS implant of FIG. 12A in an unexpanded configuration with animplant body removed for clarity, and a rear perspective view of the ISSimplant of FIG. 12A in an expanded configuration with the implant bodyremoved for clarity;

FIGS. 14A and 14B illustrate a rear elevational view and a sideperspective view of an alternate embodiment of the ISS implant of FIGS.12 and 13, in which a shaft member includes longitudinal slots thatallows wing pairs 1232, 1234, 1236, 1238 to be formed as unitaryelements.

FIGS. 15A and 15B illustrate lateral cross-sectional views taken alongline 15-15 of FIG. 14 of the ISS implant of FIGS. 13 and 14,respectively, showing the ISS implant in an unexpanded configuration(FIG. 15A) and an expanded configuration (FIG. 15B);

FIGS. 16A-16D illustrate a front perspective view of an ISS implant inaccordance with a fourteenth preferred embodiment of the presentdisclosure in an unexpanded configuration, a side elevational view ofthe ISS implant of FIG. 16A in an expanded configuration, a topperspective view of the ISS implant of FIG. 16A in an expandedconfiguration, and a top perspective view of the ISS implant of FIG. 16Ain an unexpanded configuration with a portion of an implant body removedfor clarity, respectively;

FIGS. 17A-17D illustrate a side perspective, partially exploded view ofan ISS implant in accordance with a fifteenth preferred embodiment ofthe present disclosure in an unexpanded configuration, a sideperspective view of the ISS implant of FIG. 17A in an expandedconfiguration with a distal turning wheel removed for clarity, a sideperspective view of the ISS implant of FIG. 17A in an unexpandedconfiguration, and a side perspective view of the ISS implant of FIG.17A in an expanded configuration, respectively;

FIGS. 18A-18C illustrate top perspective views of an ISS implant inaccordance with a sixteenth preferred embodiment, illustrating animplant body element in an expanded configuration (FIG. 18A), aballoon-type element (FIG. 18B), and the assembled ISS implant (FIG.18C) in an expanded configuration, respectively;

FIG. 19 illustrates a rear cross-sectional view of an ISS implant inaccordance with a seventeenth preferred embodiment of the presentdisclosure;

FIG. 20 illustrates a rear cross-sectional view of an ISS implant inaccordance with an eighteenth preferred embodiment of the presentdisclosure;

FIG. 21 illustrates a rear cross-sectional view of an ISS implant inaccordance with an nineteenth preferred embodiment of the presentdisclosure;

FIGS. 22A and 22B illustrate a side perspective view and across-sectional view taken along line 22B-22B of FIG. 22A of an ISSimplant in accordance with a twentieth preferred embodiment of thepresent disclosure, respectively;

FIG. 23 illustrates a rear cross-sectional view of an ISS implant inaccordance with an twenty-first preferred embodiment of the presentdisclosure;

FIGS. 24A and 24B illustrate a front perspective view and a sideperspective view of an ISS implant in accordance with a twenty-secondpreferred embodiment of the present disclosure in an expandedconfiguration, respectively;

FIGS. 25A and 25B illustrates top perspective views of two method stepsfor inserting the ISS implant of FIG. 24; and

FIGS. 26A and 26B illustrate top perspective views of two additionalmethod steps for inserting the ISS implant of FIG. 24.

DETAILED DESCRIPTION

Certain terminology is used in the following description for convenienceonly and is not limiting. The words “right”, “left”, “lower” and “upper”designate directions in the drawings to which reference is made. Thewords “inwardly” or “distally” and “outwardly” or “proximally” refer todirections toward and away from, respectively, the patient's body, orthe geometric center of the preferred ISS implants and related partsthereof. The words, “anterior”, “posterior”, “superior,” “inferior”,“lateral” and related words and/or phrases designate preferredpositions, directions and/or orientations in the human body to whichreference is made and are not meant to be limiting. The terminologyincludes the above-listed words, derivatives thereof and words ofsimilar import.

Referring to FIG. 1, an interspinous spacer (“ISS”) implant 100 inaccordance with a first preferred embodiment of the present disclosureincludes an inflatable interior member 110 around which is disposed anexterior member 120. The exterior member 120 is preferably inflatableand includes first, second, third, and fourth protrusions 122, 124, 126,128, respectively, which serve to limit lateral migration of the implant100 when the first and third protrusions 122, 126 are disposed on eitherside of a superior spinous process SP_(S) and when the second and fourthprotrusions 124, 128 are disposed on either side of an inferior spinousprocess SP_(I). In the first preferred embodiment, the exterior member120 is inflatable and the protrusions 122, 124, 126, 128 may also beinflatable or may be formed from solid material. In the first preferredembodiment, the exterior member 120 is formed from a compliant orsemi-compliant material, while the interior member 110 can be formedfrom compliant or non-compliant material. In addition, the protrusions122, 124, 126, 128 are preferably relatively rigid in the expandedconfiguration (FIG. 1) and may collapse such that the ISS implant 100may be introduced between the superior and inferior spinous processesSP_(S), SP_(I) through a relatively small diameter cannula (not shown)that is introduced laterally into the interspinous process space in acollapsed configuration (not shown). The interior and exterior members110, 120 are not limited to being inflatable and may be configured tomove from the unexpanded to the expanded configuration and back via amechanical assembly or a combination of inflatable and mechanicalmechanisms.

In operation, and in continuing reference to FIG. 1, the ISS implant 100is preferably inserted percutaneously between an adjacent pair ofspinous processes via a lateral approach through a relatively smallcannula in an unexpanded configuration. The inflatable member 110 andthe exterior member 120 are then inflated via a biocompatiblepressurized fluid and/or gas until the desired spacing between theadjacent spinous processes SP_(S), SP_(I) is achieved, wherein theinterior member 110 serves as a spacer and the exterior member 120serves as a securing agent due to the inclusion of the protrusions 122,124, 126, 128 and as a portion of the spacer.

Referring to FIGS. 2A-2C, an ISS implant 200 in accordance with a secondpreferred embodiment includes an inflatable member 210 having alongitudinal axis X-X extending between a proximal end and a distal end.First, second, third, and fourth deployable protrusion 222, 224, 226,228 are disposed on the inflatable member 210 adjacent superior andinferior surfaces at proximal and distal ends of the inflatable member210, respectively. Each protrusion 222, 224, 226, 228 is preferablycomprised of an elongated hollow semi-cylinder and is configured suchthat, when the inflatable member 210 is in its unexpanded, collapsed orun-inflated configuration, the third and fourth protrusions 226, 228extend distally along the longitudinal axis X-X and meet to form acylindrical dilator portion 227, whereas the first and secondprotrusions 222, 224 extend proximally along the longitudinal axis X-Xand meet to form a hollow cylinder portion 223, respectively, whichgenerally protects the inflatable member 210 during insertion. Uponinflation of the inflatable member 210, the protrusions 222, 224, 226,228 deploy to a configuration in which each is generally perpendicularto the longitudinal axis of the inflatable member 210 to therebysurround the adjacent spinous processes and limit lateral migration ofthe ISS implant 200. The ISS implant 200 of the second preferredembodiment. The protrusions 222, 224, 226, 228 are no limited toextending generally perpendicularly relative to the longitudinal axisX-X in the expanded configuration and may pinch inwardly toward theirtips to engage the spinous processes in the expanded configuration ormay stop short of extending generally perpendicularly relative to thelongitudinal axis X-X (FIG. 2B) in the expanded configuration. Suchorientations may be driven by patient anatomy and/or design of the ISSimplant 200 of the second preferred embodiment.

In operation, the ISS implant 200 is preferably inserted percutaneouslybetween an adjacent pair of spinous process via a lateral approachcorridor through a relatively small cannula. The undeployed third andfourth protrusions 226, 228 preferably form a cylinder at a proximal endof the implant and serve as a dilator for easing the ISS implant 200into the desired location via the cylindrical dilator portion 227. Theinflatable member 210 is preferably inflated once the ISS implant 200 isin a desired location with the first and second protrusions 222, 224located on one side of the adjacent spinous processes and the third andfourth protrusions 226, 228 located on the opposite side of the adjacentspinous processes, forcing the protrusions 222, 224, 226, 228 to shiftfrom the unexpanded configuration in which their longitudinal axes areparallel to the longitudinal axis X-X, to the expanded configuration inwhich their longitudinal axes are perpendicular to the longitudinal axisX-X of the inflatable member 210, such that lateral migration of the ISSimplant 200 is limited.

Referring to FIG. 3, an ISS implant 300 in accordance with a thirdpreferred embodiment includes an inflatable member 310 having alongitudinal axis Y-Y extending between a proximal end and a distal end.A relatively solid superior member 320 is disposed on a superior surfaceof the inflatable member 310 and has a first deployable protrusion 322and a first bendable portion 321 adjacent the first deployableprotrusion 322, as well as a third deployable protrusion 326 and a thirdbendable portion 325 adjacent the third deployable protrusion 326.Similarly, a relatively solid inferior member 329 is disposed on aninferior surface of the inflatable member 310 and has a seconddeployable protrusion 324 and a second bendable portion 323 adjacent thesecond deployable protrusion 324, as well as a fourth deployableprotrusion 328 and a fourth bendable portion 327 adjacent the fourthdeployable protrusion 328. The bendable portions 321, 323, 325, 327 maybe formed by providing a thin portion of material on the superior andinferior members 320, 329 adjacent to the deployable protrusions 322,324, 326, 328, respectively, resulting in living hinges being formed atthe bendable portions 321, 323, 325, 327. Upon inflation of theinflatable member 310, balloon pressure acts upon and deforms thebendable portions 321, 323, 325, 327 to force the protrusions 222, 224,226, 228 to deploy from an unexpanded configuration in which they arepositioned generally parallel to the longitudinal axis Y-Y of theinflatable member 310 to an expanded configuration in which eachprotrusion 222, 224, 226, 228 is oriented generally perpendicular to thelongitudinal axis Y-Y of the inflatable member 310 to contact orposition themselves adjacent to sides of the spinous processes.

In operation, and in continuing reference to FIG. 3, the ISS implant 300is preferably inserted percutaneously between an adjacent pair ofspinous process via a lateral approach corridor through a relativelysmall cannula or surgical pathway. The inflatable member 310 is inflatedonce the ISS implant 300 is in a desired location, deforming thebendable portions 321, 323, 325, 327 of the upper and lower members 320,329, thereby forcing the protrusions 322, 324, 326, 328 to shift fromthe unexpanded configuration in which their longitudinal axes aregenerally parallel to the longitudinal axis Y-Y of the inflatable member310, to the expanded configuration in which their longitudinal axes aregenerally perpendicular to the longitudinal axis Y-Y of the inflatablemember 210, such that lateral migration of the ISS implant 200 islimited.

Referring to FIGS. 4A-4D, a variety of balloon-type ISS implants 410,420, 430, 440 in accordance with a fourth preferred embodiment of thepresent disclosure include a first U-shaped inflatable member 412 and asecond inflatable U-shaped member 414 coupled to one another in aconfiguration that provides an H-shaped implant 410 in an expandedconfiguration. The first and second inflatable members 412, 414 can beinflated simultaneously or separately and may include a separate inletport for each member 412, 414 or a single inlet port with acommunication passage between the first and second member 412, 414. FIG.4B illustrates an ISS implant 420 that includes an inflatable memberthat assumes an X-shape in the expanded configuration for providing thedesired spacing between adjacent spinous processes SP_(S), SP_(I) whilelimiting lateral migration of the implant 420 when fully expanded. FIG.4C illustrates an ISS implant 430 that includes a U-shaped inflatablemember 430 that is folded in an unexpanded configuration prior toimplantation and inflation. Upon inflation, the ISS implant 430 assumesthe shape of a lower case alpha (α) that is well-configured to limitlateral migration of the implant 430 relative to the adjacent spinousprocesses SP_(S), SP_(I). Similarly, FIG. 4D illustrates an ISS implant440 that includes a generally straight and cylindrical inflatable member430 that is folded prior to implantation and inflation in an unexpandedconfiguration. Upon inflation, the ISS implant 440 assumes the shape ofa lower case alpha (α) that is well-configured to limit lateralmigration of the expanded implant 440 relative to the adjacent spinoutprocesses SP_(S), SP_(I). For each of the ISS implants 410, 420, 430,440 of the fourth preferred embodiment, the inflatable member can befilled with either gas, such as oxygen or air, a biocompatible cement,or fluid, such as saline. Further, the inflatable ISS implants 410, 420,430, 440 can be compliant, semi-compliant, or noncompliant. The ISSimplants 410, 420, 430, 440 may be inflated or moved from the unexpandedconfiguration to the expanded configuration utilizing nearly anybiocompatible material that is able to generally fill the ISS implants410, 420, 430, 440 to reconfigure the implant 410, 420, 430, 440 fromthe unexpanded configuration to the expanded configuration.

Referring to FIGS. 5A-5D, an ISS implant 500 in accordance with a fifthpreferred embodiment includes three linearly-arranged inflatable members510, 520, 530, including a contralateral balloon 510, a central balloon520, and an ipsalateral balloon 530. Each inflatable member 510, 520,530 includes an inlet port that may extend through the center of one ormore of the other inflatable members 510, 520, 530. The contralateralballoon 510 and ipsalateral balloon 530 preferably have a similar sizeand shape, resulting in an expanded height H_(E) that extends beyond aheight H_(I) of the interspinous space in the expanded configuration andthe central balloon 520 preferably has a height H_(C) that provides apreferred anatomical distance between the adjacent spinous processesSP_(S), SP_(I) in the implanted position.

In operation, and in continuing reference to FIGS. 5A-5D, the ISSimplant 500 is inserted percutaneously through a lateral approachcorridor with each of the inflatable members in a noninflated orunexpanded configuration. Once the implant 500 is disposed in a desiredposition with respect to the adjacent spinous processes SP_(S), SP_(I),the contralateral balloon 510, the central balloon 520, and theipsalateral balloon 530 are inflated independently of one another and inan order chosen by the user, for example, by inflating the contralateralballoon 510 first, followed by the central balloon 520, and lastly, theipsalateral balloon 530, as shown in FIGS. 5A-5C. The user may alsoselect the filling material to be used with each of the inflatablemembers 510, 520, 530, and one or more filling materials may be chosenfor one or more of the inflatable members 510, 520, 530. For instance,the user may choose to provide some cushioning between the adjacentspinous processes SP_(S), SP_(I) by filling the central balloon 520 witha hydrogel, or may provide a rigid central balloon 520 upon inflation ofa noncompliant balloon with air. The contralateral and ipsalateralballoons 510, 530 are configured to extend vertically a greater distancethan the central balloon 520 upon inflation such that lateral migrationof the ISS implant 500 is limited. Alternatively, the ISS implant 500may include a three chamber single balloon as opposed to the preferredthree separate inflatable members 510, 520, 530. In addition, theinflatable members 510, 510, 530 may be filled with variable stiffnessmaterials to tailor the elasticity of the inflatable members 510, 520,530 in the expanded configuration to provide a rigid stop between thespinous processes SP_(S), SP_(I) or to provide compliance or dampedmotion between the spinous processes SP_(S), SP_(I).

Referring to FIG. 6A-7B, an ISS implant 600 in accordance with a sixthand seventh preferred embodiment includes a central, generally rigid rodmember 630 extending along a longitudinal axis Z-Z having a proximal endand a distal end and a spacer portion 610, which may be an inflatable,semi-compliant balloon member 610 or a solid form of rigid, elastomeric,or dampening material 610′ disposed about the rod member 630. Disposedaxially about the central rod member 630 at the distal end is a firstplurality of nitinol wires 620 and disposed axially about the centralrod member 630 at the proximal end is a second plurality of nitinolwires 625. The first and second plurality of nitinol wires 620, 625include a pre-tensioned, insertion configuration (FIG. 6A), in whichtheir longitudinal axes are generally parallel to the longitudinal axisZ-Z of the ISS implant 600, and an untensioned, implanted configuration(FIG. 6B-7B), in which their longitudinal axes are generallyperpendicular to the longitudinal axis Z-Z of the ISS implant 600.

In operation, and in continuing reference to FIGS. 6A-7B, the ISSimplant 600 is preferably housed within a cylindrical tube or cannula605 during insertion, such that the longitudinal axes of the first andsecond plurality of nitinol wires 620, 625 are generally parallel to thelongitudinal axis Z-Z of the ISS implant 600. The cylindrical tube 605is preferably, percutaneously inserted through a lateral approachcorridor to a position between the adjacent spinous processes. The ISSimplant 600 may alternatively be implanted without the cannula 605 byurging the implant 600 directly through the patient's soft tissue to theimplantation site. Following implantation, the cylindrical tube orcannula 605 is removed from the patient, leaving the spacer portion 610positioned between the adjacent spinous processes SP_(S), SP_(I). As thecylindrical tube or cannula 605 is retracted, the first and secondplurality of nitinol wires 620, 625 return to their unstressed orexpanded configuration, in which their longitudinal axes are generallyperpendicular to the longitudinal axis Z-Z of the ISS implant 600,thereby limiting lateral migration of the ISS implant 600 with respectto the adjacent spinous processes SP_(S), SP_(I), In the case in whichthe spacer portion 610 is inflatable, it is then inflated with a gas,solid, or liquid material to provide the desired characteristic of theinflatable member 610 (rigid or elastic). If the spacer portion 610′ isnot inflatable, the inflating step is generally unnecessary. In such anarrangement, the compliance of the spacer element 610′ can be influencedby both choice of material as well as the inclusion of an exemption 612between a central rod member 630′ and the spacer portion 610′, as isbest shown in FIG. 7.

Referring to FIGS. 8A and 8B, an ISS implant 700 in accordance with aneighth preferred embodiment includes a central piston member 730 havinga protruding distal stop surface 732. Disposed about the central pistonmember 730 is a flexible cylindrical spacer portion 710. Disposed aboutthe central piston member 730 and adjacent to the flexible spacerportion 710 is a generally rigid tubular member 720 having a proximalstop surface 722 at its distal end. The flexible spacer member 710 ispreferably sandwiched between the distal stop surface 732 and theproximal stop surface 722 and the rigid tubular member 720 is slidablytranslatable over the central piston member 730. In an unexpandedconfiguration, the distal stop surface 732 and the proximal stop surface722 are spaced at an unexpanded length L_(U) that is typically at leastas long as a length L_(F) of the flexible spacer portion 710.

In operation, and in continuing reference to FIG. 8, the ISS implant 700is preferably inserted percutaneously through a lateral approachcorridor, preferably through a cannula, until the flexible spacerportion 710 is generally centered between the adjacent pair of spinousprocesses SP_(S), SP_(I). The central piston member 730 is thenretracted with respect to the rigid tubular member 720, thereby reducingthe unexpanded length L_(U) such that the flexible spacer portion 710 issqueezed between the distal stop surface 732 and the proximal stopsurface 722 and the flexible spacer portion is forced to fold over andsurround the lateral aspects of the adjacent spinous processes SP_(S),SP_(I). The rigid tubular member 720 is then locked with respect to thecentral piston member 730 such that the ISS implant 700 is limited fromlateral migration relative to the spinous processes SP_(S), SP_(I). Inthis expanded configuration, the distal stop surface 732 and theproximal stop surface 722 are spaced at an expanded length L_(E) that issmaller than the length L_(F) of the flexible spacer portion 710 and theflexible spacer portion 710 has an expanded height H_(E) that is greaterthan a height H_(S) of the distal and proximal stop surfaces H_(D),H_(P).

Referring to FIG. 9, an ISS implant 800 in accordance with a ninthpreferred embodiment is comprised of an inflatable balloon-type implant800 having a central portion 800 a with a reduced size or height H_(C)with respect to first and second enlarged end portions H_(EP) in anexpanded configuration. The ISS implant 800 further includes acannulated interior configured to slide over a guidewire 810. Inoperation, the guidewire 810 is inserted through the posterior of apatient and glides along the interspinous space between the adjacentspinous processes SP_(S), SP_(I), preferably without perforating thesupraspinous ligament SSL. The interspinous ligament ISL is thenpreferably perforated by the guidewire 810. The ISS implant 800 is theninserted over the guidewire 810 into the interspinous space and inflatedsuch that the enlarged portions 800 b of the ISS implant 800 arepositioned contralaterally and ipsilaterally of the interspinous spaceto limit movement of the ISS implant 800 relative to the spinousprocesses SP_(S), SP_(I).

Referring to FIG. 10, an ISS implant 900 in accordance with a tenthpreferred embodiment is comprised of an inflatable implant configuredfor percutaneous insertion over a guidewire 910. The ISS implant 900includes a cannulated interior configured for delivering the ISS implant900 over the guidewire 910. The guidewire 910 is preferably insertedlaterally into the interspinous space between the adjacent spinousprocesses SP_(S), SP_(I) and perforates the interspinous ligament. TheISS implant 900 is then delivered over the guidewire 910 into positionbetween the spinous processes SP_(S), SP_(I). The ISS implant 900preferably includes lateral inflatable members 902 that are preferablyconfigured to expand to surround the lateral aspects of the spinousprocesses SP_(S), SP_(I) such that lateral migration of the ISS implant900 is limited. Alternatively, the lateral members 902 may bemechanically deployable. The ISS implant 900 also preferably includes adampening member 904 generally centrally located on an exterior surfacethat contacts the adjacent spinous processes SP_(S), SP_(I) in theimplanted position.

In reference to FIG. 11, an ISS implant 1000 in accordance with aneleventh preferred embodiment includes a rigid catheter 1010 aroundwhich is disposed a proximal expandable member 1020, a centralexpandable member 1030, and a distal expandable member 1040. Theproximal and distal expandable members 1020, 1040 may assume the form ofa stent, a balloon-type expandable member, a self-expanding foamstructure that expands when resistance provided by the catheter 1010 isremoved, locking-stopping bumps or toruses, or members that areexpandable by a pulling mechanism. The central expandable member 1030may assume the form of a balloon or a multi-lumen balloon havingdiffering compliances, or a self-expanding foam structure. In operation,the ISS implant 1000 is preferably inserted percutaneously from alateral approach corridor and the proximal, central, and distalexpandable members 1020, 1030, 1040 are expanded. In the eleventhpreferred embodiment in which the proximal and distal expandable members1020, 1040 are stent-like expandable forms, the stent portions 1020,1040 may be formed by removal of material and the formation of astent-pattern in the catheter 1010 itself, or stent members may beapplied over the catheter 1010 and around a portion that houses adeployable balloon 1030 for expanding the stent portions 1020, 1040. Inthe preferred embodiment, the expandable members 1020, 1030, 1040 areenlarged by a pulling mechanism.

In reference to FIG. 12, an ISS implant 1100 in accordance with atwelfth preferred embodiment includes a cross-section of circular, oval,or rectangular and is configured for insertion between the adjacentspinous processes SP_(S), SP_(I) while enclosed within a tubularinsertion sleeve 1111. The ISS implant 1100 includes a pair of proximalwings 1110, 1112 and a pair of distal wings (not shown). Each pair ofwings 1110, 1112 is configured to be rotatable about a joint (not shown)in a plane that is generally parallel to the medial plane. In the sameplanes proximal and distal, a rod shaped element (not shown) isconnected with a rotatable central shaft 1130. Upon rotation of thecentral shaft 1130, the rod shaped element 1130 forces the proximal anddistal pairs of wings 1110, 1112 to rotate about their joints and extendinto a position in which they serve as lateral migration stops to limitmovement of the ISS implant 1100 relative to the spinous processesSP_(S), SP_(I).

Referring to FIGS. 13A-14B, an ISS implant 1200 of a thirteenthpreferred embodiment includes an implant body 1210, a central rod 1220having proximal and distal ends and a longitudinal axis M-M extendingtherebetween. A first wing 1232 and a second wing 1234 are preferablycoupled to the central rod 1220 near the proximal end, and a third wing1236 and a fourth wing 1238 are preferably coupled to the rotatablecentral rod 1220 near the distal end. The wings 1232, 1234, 1236, 1238are preferably formed of a resilient or deformable material and areconfigured to assume an undeployed state or configuration (FIGS. 13A and13B), in which they are at least partially wrapped around the centralrod 1220, as well as a deployed state (FIGS. 13C-14B), in which they areunwound from the central rod 1220 via rotation of the central rod 1220such that the wings 1232, 1234, 1236, 1238 are deployed to extend awayfrom the implant body 1210 through a first slot 1242, a second slot1244, a third slot 1246, and a fourth slot 1248, respectively, formedthrough the outer surface of the implant body 1210 and positioned so asto accommodate the deployment of the wings 1232, 1234, 1236, 1238 awayfrom the outer surface of the implant body 1210. In operation, the ISSimplant 1200 is preferably inserted percutaneously between the adjacentspinous processes SP_(S), SP_(I) via a lateral approach corridor,typically through a cannula (not shown). An instrument engages anengagement feature 1222 on the proximal end of the central rod 1220 andis rotated to turn the central rod 1210 and, thereby, undeform orunstress the wings 1232, 1234, 1236, 1238 to thereby allow them todeploy through the slots 1242, 1244, 1246, 1248, respectively and serveas lateral migration stops for the positioning of the ISS implant 1200with respect to the interspinous space and the adjacent spinousprocesses SP_(S), SP_(I). Alternatively, as is shown in FIGS. 15A and15B, the shaft 1222 member is formed to include longitudinal slots 1221through an external sleeve 1223 that allow the wing pairs 1236, 1238,and the wing pairs 1232, 1234, to be formed as unitary elements and tobe positioned generally within the bounds of the external sleeve 1223 inthe undeployed configuration.

In reference to FIGS. 16A-16D, an ISS implant 1300 in accordance with afourteenth preferred embodiment includes an implant body 1310, a centralshaft 1320 having a proximal end and a distal end, wherein the proximalend further includes an instrument engagement feature 1360 and thecentral shaft 1320 further includes a first worm gear 1322 disposed nearits proximal end and operatively connected to a first pair of wings1332, 1334 and a second worm gear 1324 disposed at its distal end andoperatively connected to a second pair of wings 1336, 1338. The firstand second pairs of wings 1332, 1334, 1336, 1338 are operativelyconnected to the first and second worm gears 1322, 1324, respectively,via the inclusion at the base of each wing 1332, 1334, 1336, 1338 of asnail gear 1352, 1354, 1356, 1358, respectively. In operation, the ISSimplant 1300 is preferably inserted percutaneously through a lateralapproach corridor and placed between the spinous processes SP_(S),SP_(I). An instrument (not shown) engages and is turned to rotate theinstrument engagement feature 1360 and thereby force the first andsecond worm gears 1322, 1324 to engage the snail gears 1352, 1354, 1356,1358 to thereby deploy the wings 1332, 1334, 1336, 1338 through a rangeof approximately ninety degrees (90°), from a position in which thelongitudinal axes of the wings 1332, 1334, 1336, 1338 are generallyparallel to a longitudinal axis N-N of the implant body 1310 to aposition in which the longitudinal axes of the wings 1332, 1334, 1336,1338 are generally perpendicular to the longitudinal axis N-N of theimplant body 1310.

In reference to FIG. 17A-17D, an ISS implant 1400 in accordance with afifteenth preferred embodiment includes an implant body 1410 having alongitudinal axis O-O extending between a proximal end and a distal endand a central rod 1480 disposed through the center of the implant body1410 that extends along the longitudinal axis O-O.

The central rod 1480 is operatively coupled at its proximal end to aproximal turning wheel 1450 and is operatively coupled at its distal endto a distal turning wheel 1460 such that, upon rotation of the proximalturning wheel 1450, i.e., via the rotation of an instrument temporarilycoupled to an instrument engagement feature (not shown) formed at theproximal end of the proximal turning wheel 1450, the proximal turningwheel 1450, the central rod 1480, and the distal turning wheel 1460 areeach forced to rotate with respect to the implant body 1410. In thepreferred embodiment, the distal turning wheel 1460 includes a bulletnosed tip to ease the insertion of the ISS implant 1400 and/or applydistraction during the insertion of the ISS implant 1400. A firstproximal slot 1422 and a second proximal slot 1424 are preferably formedadjacent the proximal end of the implant body 1410 and the longitudinalaxes of the first and second proximal slots 1422, 1424 are orientedgenerally perpendicular to the longitudinal axis O-O of the implant body1410. Similarly, a first distal slot 1426 and a second distal slot 1428are formed adjacent the distal end of the implant body 1410 and thelongitudinal axes of the first and second distal slots 1426, 1428 alsogenerally oriented perpendicular to the longitudinal axis O-O of theimplant body 1410. First and second proximal wings 1432, 1434 and firstand second distal wings 1436, 1438 are positioned in the first andsecond proximal slots 1422, 1424 and the first and second distal slots1426, 1428, respectively. Each of the first and second proximal wings1432, 1434 and the first and second distal wings 1436, 1438 includes apost 1431, 1433, 1435, 1437, respectively, that protrudes into a slot1462, 1464, 1466, 1468, respectively, formed on the interior surface ofthe proximal and distal turning wheels 1450, 1460. The wings 1432, 1434,1436, 1438 are preferably generally contained within the slots 1462,1464, 1466, 1468 in the unexpanded configuration and extend from theslots 1462, 1464, 1466, 1468 in the expanded configuration.

In operation, and in continuing reference to FIGS. 17A-17D, the ISSimplant 1400 is preferably inserted percutaneously through a lateralapproach corridor such that the implant body 1410 is positioned betweenthe spinous processes SP_(S), SP_(I). An instrument is coupled to theinstrument engagement feature on the proximal turning wheel 1450 and isrotated, forcing the proximal turning wheel 1450, the central rod 1480,and the distal turning wheel 460 to rotate, preferably approximatelyninety to one hundred degrees (90-100°), with respect to the implantbody 1410. During rotation of the proximal turning wheel 1450, thecentral rod 1480, and the distal turning wheel 1460, the posts 1431,1433, 1435, 1437 are forced to interact with, preferably slide within,the rotating slots 1462, 1464, 1466, 1468 formed on the interior surfaceof the proximal and distal turning wheels 1450, 1460, thereby forcingthe wings 1432, 1434, 1436, 1438 to translate within the first andsecond proximal slots 1422, 1424 and the first and second distal slots1426, 1428 formed at the proximal and distal ends of the implant body1410, thereby deploying the wings 1432, 1434, 1436, 1438 outwardly withrespect to the exterior surface of the implant body 1410 to serve aslateral migration stops to limit migration of the ISS implant 1400 withrespect to the spinous processes SP_(S), SP_(I).

In reference to FIG. 18, an ISS implant 1500 in accordance with asixteenth preferred embodiment includes a balloon-type element 1510disposed about a mechanically expandable ISS implant 1400 such as thatof the fifteenth preferred embodiment. The balloon-type element 1510 mayalso be disposed about ISS implants 1300, 1200, 1100 that are similar tothe twelfth, thirteenth and fourteenth preferred embodiments. For thesake of illustration, the ISS implant 1500 includes the balloon-typeelement 1510 and the ISS implant 1400 of the fifteenth preferredembodiment, but may assume a variety of different configurations. Theinflatable balloon-type element 1510 is disposed about the implant body1410 in a position such that, upon implantation, the balloon-typeelement 1510 is positioned between the adjacent spinous processesSP_(S), SP_(I). The balloon-type element 1510 may be pre-inflated priorto implantation of the ISS implant 1500 or may be inflated subsequent toinsertion of the ISS implant 1500 between the adjacent spinous processesSP_(S), SP_(I). The inclusion of the balloon-type element 1510 enablesthe ISS implant 1500 to achieve significant bony contact to the spinousprocesses SP_(S), SP_(I), resulting in a contact surface with generallyequally distributed stress for the bone and a limitation of stress peaksor risers, which may in some cases lead to bone resorption and loss ofspacer height, while at the same time absorbing a portion of the stressimparted to the implant body 1510. The balloon-type element 1510 may befilled with gas or liquid or solid dampening material. A liquid materialthat is chosen to cure to a hard material subsequent to implantation andinflation can maximize surface area of contact between the spinousprocesses SP_(S), SP_(I) and the ISS implant 1500. The choice of asofter fill material, such as silicone or polyurethane, enables theabsorption of stress and the dampening of loads imparted to the portionsof the spinous processes SP_(S), SP_(I) that contact the ISS implant1500, thereby decreasing the risk or adaptation or erosion of thespinous processes SP_(S), SP_(I).

In reference to FIG. 19, an ISS implant 1600 in accordance with aseventeenth preferred embodiment includes two W-folded plates that serveas a dampening spacer between the adjacent spinous processes SP_(S),SP_(I). Features of the ISS implant 1600 can further be combined withthe ISS implants 1100, 1200, 1300, 1400 twelfth, thirteenth, fourteenthand fifteenth preferred embodiments in that a form similar to the twoW-folded plates can be formed into or replace the spacer bodies of theISS implants 1100, 1200, 1300, 1400.

Referring to FIG. 20, an ISS implant 1700 in accordance with aneighteenth preferred embodiment includes a spacer portion 1710 with ahard foam coating 1720 on at least the portions of the spacer portion1710 that come into contact with the adjacent spinous processes SP_(S),SP_(I). The hard foam 1720 is compressible such that the surface area ofcontact between the spinous processes SP_(S), SP_(I) and the ISS implant1700 is maximized to provide an anatomical fit and a generally equaldistribution of stress to the spinous processes SP_(S), SP_(I) in theimplanted position.

In reference to FIG. 21, an ISS implant 1800 of a nineteenth preferredembodiment includes a spacer portion 1810 and a flexible membrane 1820filled with small granulae surrounding at least the portions of thespacer portion 1810 that come into contact with the adjacent spinousprocesses SP_(S), SP_(I). The granulae 1820 can be formed usingmaterials such as biocompatible polymers such as PEEK, PEKK,polyurethane, etc. Under load, the individual granules within theflexible membrane 1820 that experience the largest amount of force aredisplaced laterally such that the anatomy of the spinous processesSP_(S), SP_(I) is accommodated and the surface area of contact betweenthe spinous processes SP_(S), SP_(I) and the ISS implant 1800 ismaximized. The inclusion of a flexible membrane 1820 filled withgranulae can further be incorporated into the design of others of thepreferred ISS implants, which were described above.

Referring to FIGS. 22A and 22B, an ISS implant 1900 in accordance with atwentieth preferred embodiment includes a spacer portion 1810 and aflexible membrane filled with fiber-shaped material 1920 surrounding atleast the portions of the spacer portion 1910 that come into contactwith interspinous processes SP_(S), SP_(I). The fiber-shaped material1920 can be formed using materials such as biocompatible polymers suchas PEEK, PEKK, and polyurethane. Under load, the individual fiberswithin the flexible membrane or fiber-shaped material 1920 thatexperience the largest amount of force are displaced laterally such thatthe precise anatomy of the spinous processes SP_(S), SP_(I) is generallyaccommodated and the surface area of contact between the spinousprocesses SP_(S), SP_(I) and the ISS implant 1900 is maximized. Theinclusion of the flexible membrane filled with fiber-shaped material1920 can further be incorporated into the design of the ISS implants ofthe above-described preferred embodiments.

Referring to FIG. 23, an ISS implant 2000 in accordance with atwenty-first preferred embodiment includes a rigid spacer portion 2010and a flexible membrane 2020 that surrounds at least the portions of thespacer portion 2010 that come into contact with the adjacent spinousprocesses SP_(S), SP_(I). A sealed chamber is provided between thespacer portion 2010 and the flexible membrane 2020 that can be filledwith bone cement 2030 upon insertion of the ISS implant 1900 between thespinous processes SP_(S), SP_(I). As the chamber is filled, the cement2030 is distributed in such a way that the surface area of contactbetween the ISS implant 2000 and the spinous processes SP_(S), SP_(I) ismaximized. Following implantation, the flexible membrane 2020 isconfigured to absorb some load and provide a dampening aspect to the ISSimplant 2000. The inclusion of a flexible membrane 2020 and a sealedchamber between the spacer portion 2010 and the flexible membrane 2020can further be incorporated into the design of ISS implants of nearlyany of the above-described preferred embodiments.

Referring to FIGS. 24A-26B, an ISS implant 2100 and corresponding methodin accordance with a twenty-second preferred embodiment is comprised ofan hourglass-shaped balloon-type member 2100 configured to be introducedpercutaneously between the adjacent spinous processes SP_(S), SP_(I) ina deflated or unexpanded configuration and, upon desired positioningwith respect to the adjacent spinous processes SP_(S), SP_(I), filledwith a hardening fluid to a point at which a middle portion 2100 areaches a diameter d adequate to treat the indication or to generallyrecreate an anatomically accurate distance between the adjacent spinousprocesses SP_(S), SP_(I). An enlarged diameter D of lateral portions2100 b of the ISS implant 2100 serve as lateral migration stops togenerally limit lateral movement of the ISS implant 2100 relative to thespinous processes SP_(S), SP_(I).

Referring to FIGS. 23A-24B, in operation, a guidewire 2110 is placedbetween the adjacent spinous processes SP_(S), SP_(I) via a lateralapproach corridor. In reference to FIG. 25B, a cannulated protectionsleeve 2120 is placed over the guidewire 2110 until the distal end ofthe cannulated protection sleeve 2120 advances distally past theinterspinous space between the adjacent spinous processes SP_(S), SP_(I)by approximately two centimeters (2 cm). The guidewire 2110 is thenremoved. In reference to FIG. 26A, the ISS implant 2100, in a folded andunexpanded configuration and attached to an implant cannula 2130 (shownin FIG. 26B), is inserted distally through the cannulated protectionsleeve 2120 until the distal end of the ISS implant 2100 reaches thedistal end of the cannulated protection sleeve 2120, at which point thecannulated protection sleeve 2120 is removed. In reference to FIG. 26B,a hardening radiopaque material in a liquid phase, such as liquidsilicone, PMMA, or another liquid, is injected into the ISS implant 2100through the implant cannula 2130 until a specific pressure is reached,such as a pressure at which it is known that the ISS implant 2100 isinflated to a specific size and in contact with a desired amount ofsurface area of the adjacent spinous processes SP_(S), SP_(I). Once theliquid filling material has hardened, the implant cannula 2130 is brokenaway from the ISS implant 2100 and removed from the patient.

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. It is understood, therefore, that thisdisclosure is not limited to the particular embodiments disclosed, butit is intended to cover modifications within the spirit and scope of thepresent disclosure as defined by the present description.

What is claimed:
 1. An interspinous process spacer for implantation inan interspinous space between a superior spinous process and an inferiorspinous process, the interspinous process spacer comprising: an implantbody; a central shaft extending through the implant body, the centralshaft having a distal end, a proximal end, and a longitudinal axisextending between the proximal end and the distal end, the central shaftbeing rotatable, and the central shaft further comprising a proximalworm gear disposed near the proximal end and including proximal threadsand a distal worm gear disposed near the distal end and including distalthreads, the proximal threads and the distal threads having oppositeorientations; a first proximal gear set comprising at least one gear,the first proximal gear set operatively coupled to the central shaftproximate the proximal end; a first distal gear set comprising at leastone gear, the first distal gear set operatively coupled to the centralshaft proximate the distal end; a first proximal wing operativelycoupled to the first proximal gear set wherein the first proximal wingis extendable in a plane perpendicular to the longitudinal axis; and afirst distal wing operatively coupled to the first distal gear setwherein the first distal wing is extendable in a plane perpendicular tothe longitudinal axis, wherein the first distal wing and the firstproximal wing withdraw within the bounds of the implant body in theunexpanded configuration, and wherein the first distal wing and thefirst proximal wing extend beyond the bounds of the implant body in theexpanded configuration.
 2. The interspinous process spacer of claim 1wherein the proximal end further comprises a proximal turning wheel. 3.The interspinous process spacer of claim 2 wherein the distal endfurther comprises a distal turning wheel.
 4. The interspinous processspacer of claim 3 wherein the distal turning wheel further comprises ashaped tip for ease of insertion.
 5. The interspinous process spacer ofclaim 1, wherein the first proximal wing is extendable in an oppositedirection from the first distal wing during expansion.
 6. Theinterspinous process spacer of claim 5, wherein the first proximal wingforms a proximal opening and the first distal wing forms a distalopening during expansion.
 7. The interspinous process spacer of claim 1wherein at least one gear set from among the group consisting of thefirst proximal gear set and the first distal gear set further comprises:the worm gear operatively coupled to the central shaft; and a snail gearoperatively coupled to a base portion of a wing, wherein rotation of thecentral shaft causes rotation of the worm gear causing rotation of thesnail gear causing the wing to either extend or withdraw depending onthe direction of rotation of the central shaft.
 8. The interspinousprocess spacer of claim 1 wherein the proximal end further comprises aninstrument engagement feature for turning the central shaft.